Delineation of Gold Mineral Potential Zone Using High Resolution
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logy eo & G OPEN ACCESS Freely available online G e f o p o l h a y s n r i c u s o J Journal of Geology & Geophysics ISSN: 2381-8719 Research Article Delineation of Gold Mineral Potential Zone Using High Resolution Aeromagnetic Data Over Part of Kano State, Nigeria Eshimiakhe Daniel*, Raimi Jimoh and Kola Lawal Ahmadu Bello University, Zaria, Nigeria ABSTRACT The study of the geometry and kinematics of deep geological structures, bearing mineralization has advanced greatly by the aggressive progress of geophysical techniques over the last decades. The mineralization zones located in the Shanono local government area of Kano state Nigeria has its genesis controlled by shear zones. This research was aimed at delineating and characterizing subsurface geologic structures around the study area. Both qualitative and quantitative analysis of aeromagnetic data has provided defined distinct pattern of the magnetic signatures. Euler solution of the aeromagnetic data with structural index one, revealed the presence of the major tectonic trends of anomalies in the NE-SW and NW-SE directions. The trends of few of these structures are observed to be similar to fracture orientations in the Nigerian basement complex. These structures control the emplacement of the gold mineralization as these provides the pathways to flow of mineral rich fluid within the host rocks of the study area. Keywords: Gold; Fractures; Lineaments INTRODUCTION dangerous conditions in the absence of the required safe mining regulations to safeguard the operations [5]. The environmental and Nigeria has been known to have a long history of mining and the health implication of mining have long been studied and scientific country was a prominent exporter of minerals such as tin, coal, and literature is full of documented cases of damage to the environment kaolin. Gold is generally found in Nigeria as alluvial and eluvial and human health directly linked to the mining-related pollution [8- placers and primary veins from several parts of supracrustal (schist) 12]. Despite the dangers that this mining activities causes, artisanal belts, in the northwest and southwest of the country [1]. Several gold mining operation continue to spread due to the unattractive authors have studied the gold mineralization in Nigeria and the nature of other means of livelihoods such as farming and fishing host rocks [2,3]. The most occurrences of such gold minerilization in the rural areas where such mineral exists [13]. These dangers are found in the Maru, Anka, Malele, Tsohon Birnin Gwari-Kwaga, have led to the advanced use of geophysical methods to delineate Gurmana, Bin Yauri, Okolom-Dogondaji and Iperindo areas, all fault lines associated with minerals, so as reduce the environmental associated with the schist belts of northwest and southwest Nigeria damages caused by artisanal miners. [1]. All these areas are spatially related to the two fault systems in the region [4] the gold-bearing veins, reefs and stringers are Geophysical techniques (gravity, magnetics and electromagnetics often localized by brittle and ductile fault structures or planes of etc.) have been widely used to get subsurface information of the schistosity that traverse phyllites, schists, quartzites, gneisses and Earth, without engaging in invasive digging. It has been utilized contact aureoles of granitoid masses. to solve many problems such as geotechnical, and exploration etc. The basic step is first to identify the physical property, that is, Artisanal mining in Nigeria, has being a means of livelihood diagnostic of the sought geologic structure in the area of study. The adopted primarily in rural areas [5]. This is sometimes called appropriate geophysical survey is then employed, then field data the informal sector, which is outside the legal and regulatory are acquired and plotted. In some cases, the information needed framework [6]. When not properly done, artisanal mining can be to solve the problem may be obtained directly from these plots, but viewed negatively by governments and environmentalists, because in most cases, more information about the subsurface is required. of its potential for environmental damage, social disruption, and conflicts [7]. Most of these miner’s work in very difficult and often Geophysics has been evolving, and new methods of automating *Correspondence to: Eshimiakhe Daniel, Ahmadu Bello University, Zaria, Nigeria, E-mail: [email protected] Received: September 12, 2019; Accepted: October 4, 2019; Published: October 11, 2019 Citation: Daniel E, Jimoh R, Lawal K (2019) Delineation of Gold Mineral Potential Zone Using High Resolution Aeromagnetic Data Over Part of Kano State, Nigeria, J Geol Geophys 8:464. 10.35248/2381-8719.464 Copyright: © 2019 Daniel E, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. J Geol Geophys, Vol. 8 Iss. 4 No: 464 1 Daniel E, et al. OPEN ACCESS Freely available online geophysics, such as resistivity, magnetometry, very low frequency, Geology of the study area gravity and seismology, are being developed. The study of the Shanono local government area of Kano state lies on the Basement earth’s magnetic field, is one of the oldest branches of geophysics. Complex rocks of northern Nigeria (Figure 2). The Nigerian It has been known for more than three centuries that the earth basement complex is made up of gneisses, migmatites, and behaves as a large and somewhat irregular magnet [14]. However, metasediments of Proterozoic age which have been intruded by a the ground magnetic is always being studied for precise mapping so series of granitic rocks of Late Precambrian to Lower Palaeozoic as to understand the subsurface geology of an area. This technique age. These rocks have been variably metamorphosed and granitized basically requires measurements of the amplitude of magnetic through at least two tectonic-metamorphic cycles converted to components at discrete points along traverses distributed regularly migmatites and granite-gneiss [18,19]. Falconer et al. have reported throughout the survey area of interest. the occurrence of rocks of the Younger Granites series [20], which Aeromagnetic survey is carried out using a magnetometer on board are Jurassic in age, as well as volcanic, and occasional younger dikes. or towed behind an aircraft, a ship or Boat. The principle is different Nigerian schist belts are complexly deformed with earlier folds as compared to a ground magnetic survey carried out with a hand- being refolded by later once and there are some similarities of the held magnetometer in the sense that it covers much larger areas dominant deformations in all the belts [21]. The Kazaure schist of the earth’s for regional reconnaissance. The airborne magnetic belt is characterized by upright isoclinal folds with NNE-SSW axial survey has been used so well in the mineral exploration industry, planes and well-developed cleavage formed during the Pan-African basically for the characterization of mineralization zones in most orogeny, and relict recumbent isoclinal folds with N-S trending parts of the world and as the secondary tool in gold exploration axial plane mostly obliterated [21]. The Malumfashi schist belt is in Nigeria [15,16]. The success of this method is derived from the characterized by an early ENE-WSW foliation largely obliterated, unique signatures that are produced by the mineralization zones and Pan-African orogenic imprints of light to isoclinal ENE-WSW making it possible to distinguish them from the host rock. folds with N-S axial plane [22]. The role of aeromagnetic method in mineral exploration varies Gold mineralization in the study area occurs in a variety of host from delineation structures like faults, folds, contacts, shear zones rocks, but is generally related to the supracrustal schist belts. and intrusions to automated detection of porphyry and favorable areas of ore deposits. There are various enhancement techniques MATERIALS AND METHODS that can help achieve objectives. Data source Location, climate and vegetation of the study area Four high-resolution aeromagnetic maps (HRAM) were acquired The Shanono local government area lies on latitudes 11.962 N to from the Nigerian Geological Survey Agency (NGSA). These 12.264 N and longitudes 7.979 E to 7.980 E (Figure 1) which is sheets include; sheets 56 (Yashi), 57 (Shanono and Bichi), 79 north-east of Kano state, Nigeria. The inhabitants are agrarian, (Malumfashi) and 80 (Karaye). The aeromagnetic data collected by however, with the discovery of traces of minerals at Shanono, they the NGSA between 2005 and 2009 at a flight altitude of 80 m embrace artisanal mining for gold in the dry season to complement along a series of NE–SW flight lines with a spacing of 500 m. The farming. According to Olofin [17], the climate of Kano state is data were made available in the form of a contoured map on a scale the tropical wet and dry type, although some climate changes are of 1:100,000 grid file. The grid after been superimposed together, believed to have occurred. The natural vegetation of Shanono local extend from 110 30’ N-120 30’ N and from 70 30’ E-80 30’ E, covering government area is the Sudan Savannah type. Figure 1: Map showing the location of the study area and environment (Adamu, 2018). J Geol Geophys, Vol. 8 Iss. 4 No: 464 2 Daniel E, et al. OPEN ACCESS Freely available online Figure 2: Geologic map of Kano State. Figure 3: Total magnetic intensity (TMI) of the study area gridded on the oasis montaj software using a grid cell size of 0.00225 degrees (250 m) with the two black points indicating the study area. g kk= F f x, y the study area. The magnetic field intensity ranges from 33901 to ( xy) ( ) 33099 nT (Figure 3).